For efficient electricity utilization, multistage power conversions (AC-DC conversion, and frequency conversion) are performed in the process from power generation to power consumption, and many semiconductor power devices are used. Reduction of power loss in these semiconductor power devices is an important key to energy saving.
Diamond has a band gap broader than that of silicon used commonly as a semiconductor material, has high properties in terms of melting point, thermal conductivity, dielectric breakdown durability, carrier speed limit, hardness/elastic constant, chemical stability, and radiation-proofness, and has a very high potential as a material of electric devices, particularly, semiconductor power devices.
However, there have been problems with diamond. It is difficult to dope diamond with an impurity by ion implantation and the like that are employed for other semiconductor materials, which is an obstacle against selective formation of an n-type impurity-doped region, and against device design to the purpose.
With regard to these problems, the present inventors have succeeded in selective formation of n-type impurity-doped diamond, by promoting crystal growth of an n-type impurity-doped diamond region from a starting point that is set at a base angle of a step-like shape formed over a diamond substrate having a controlled crystal face, and have made proposals for realization of diamond semiconductor devices (see International Publication No. WO 2010/001705).
However, what has remained unachieved is a specific method for constructing an electronic device composed of various elements including a semiconductor power device, and there have been demands for development of a diamond semiconductor device allowing a greater degree of latitude in device design, and a method for manufacturing such a diamond semiconductor device. Particularly, if it is possible to realize selective integral formation of a diamond region doped with an impurity at an intended location and an undoped diamond insulation region, and to thereby construct an element structure that enables element isolation by means of these regions, it is possible to realize a diamond semiconductor device having a FET (field effect transistor) structure in which, for example, a region around a doped region is isolated by an insulation region, and only the element region around the doped region is defined as a channel length. Therefore, such selective integral formation will make it possible to greatly increase the degree of latitude in device design, and to efficiently manufacture a diamond semiconductor device.